rename workdir to cwd throughout codebase

Completes the rename started with the 9P file change.

Go API: WorkDir→CWD, SetWorkDir→SetCWD, WorkDirSetter→CWDSetter.
Unexported: workdir→cwd in fields, params, locals.
Template: {{.WorkDir}}→{{.CWD}}.
Docs: ARCHITECTURE.md, PLANNING.md, README.md, IDEAS.md.

doc/ARCHITECTURE.md

@@ -43,7 +43,7 @@ All tool servers implement the same `tools.Server` interface regardless of wheth
 
 Each built-in server package exports a `Decl` function (`func Decl(...) func() tools.Server`) — a parameterized factory that produces a fresh server instance. `tools.NewDispatcherFunc` takes a map of name→Decl result and returns a `func() tools.Dispatcher` suitable for `agent.AgentCoreConfig.NewDispatcher`. `tools.NewServer(client)` wraps an `mcp.Client` as a `tools.Server`.
 
-`execute.Decl(workdir string)` accepts a working directory that is set as `cmd.Dir` for sandboxed commands and used to expand `{CWD}` in the sandbox config. Pass `""` to fall back to `os.Getwd()`.
+`execute.Decl(cwd string)` accepts a working directory that is set as `cmd.Dir` for sandboxed commands and used to expand `{CWD}` in the sandbox config. Pass `""` to fall back to `os.Getwd()`.
 
 **Adding a new tool server:**
 1. Implement `tools.Server` in a new package under `pkg/tools/`
@@ -123,22 +123,22 @@ See [PLANNING.md](PLANNING.md) for the full design rationale.
 
 ```go
 newDispatcher := tools.NewDispatcherFunc(map[string]func() tools.Server{
-    "execute":   execute.Decl(workdir),  // "" falls back to os.Getwd()
+    "execute":   execute.Decl(cwd),  // "" falls back to os.Getwd()
     "reasoning": reasoning.Decl(),
 })
 
-env := agent.BuildAgentEnv(cfg, newDispatcher(), workdir)  // also connects MCP servers from cfg
+env := agent.BuildAgentEnv(cfg, newDispatcher(), cwd)  // also connects MCP servers from cfg
 
 core := agent.NewAgentCore(agent.AgentCoreConfig{
     Backend:       be,
-    WorkDir:       workdir,
+    CWD:           cwd,
     Env:           env,
     NewDispatcher: newDispatcher,
     // ...
 })
 ```
 
-`BuildAgentEnv` adds MCP servers from the config on top of the pre-registered servers. On `/agent` switches, `NewDispatcher` is called to produce a fresh dispatcher — all servers (built-in and MCP) are torn down and recreated for the new agent config. `WorkDir` is preserved across switches.
+`BuildAgentEnv` adds MCP servers from the config on top of the pre-registered servers. On `/agent` switches, `NewDispatcher` is called to produce a fresh dispatcher — all servers (built-in and MCP) are torn down and recreated for the new agent config. `CWD` is preserved across switches.
 
 After connecting MCP servers, `BuildAgentEnv` scans the tool list for `task_create`. If found, it wires a `dispatchPlanBackend` to the reasoning server's `Plan` field via `tools.PlanBackendSetter`. If not found, it wires any fallback passed via `WithFallbackPlanBackend`. This auto-wiring runs on every agent start and `/agent` switch.
 

doc/IDEAS.md

@@ -32,15 +32,15 @@ Three sessions with specialized agent configs run a feedback loop. The reviewer
 
 ```sh
 #!/bin/sh
-workdir=${1:?usage: $0 <workdir>}
+cwd=${1:?usage: $0 <cwd>}
 cd ~/mnt/ollie
 
 # Count existing sessions so we can identify the newly created ones by offset.
 n=$(ls s/ | wc -l)
 
-echo "new agent=developer cwd=$workdir" > ctl
-echo "new agent=reviewer  cwd=$workdir" > ctl
-echo "new agent=tester    cwd=$workdir" > ctl
+echo "new agent=developer cwd=$cwd" > ctl
+echo "new agent=reviewer  cwd=$cwd" > ctl
+echo "new agent=tester    cwd=$cwd" > ctl
 
 dev=$(ls s/ | sort | sed -n "$((n+1))p")
 rev=$(ls s/ | sort | sed -n "$((n+2))p")
@@ -117,10 +117,10 @@ _spawn_lock  = threading.Lock()
 def session_ids():
     return {e.name for e in (BASE / "s").iterdir() if e.is_dir()}
 
-def spawn_session(agent="default", workdir=""):
+def spawn_session(agent="default", cwd=""):
     with _spawn_lock:
         before = session_ids()
-        (BASE / "ctl").write_text(f"new agent={agent} cwd={workdir}\n")
+        (BASE / "ctl").write_text(f"new agent={agent} cwd={cwd}\n")
         while True:
             new = session_ids() - before
             if new:
@@ -139,10 +139,10 @@ def wait_reply(sid):
 
 def run_subagent(spec):
     agent   = spec.get("agent", "default")
-    workdir = spec.get("workdir", "")
+    cwd     = spec.get("cwd", "")
     context = spec.get("context", "")
     task    = spec.get("task", "")
-    sid     = spawn_session(agent, workdir)
+    sid     = spawn_session(agent, cwd)
     try:
         prompt = f"{context}\n\n{task}".strip() if context else task
         (BASE / "s" / sid / "prompt").write_text(prompt)

doc/PLANNING.md

@@ -42,7 +42,7 @@ import cycles: reasoning → tools, agent → tools, agent ↛ reasoning.
 Consumers can supply a fallback backend via `agent.WithFallbackPlanBackend(b)`:
 
 ```go
-env := agent.BuildAgentEnv(cfg, d, workdir, agent.WithFallbackPlanBackend(myFallback))
+env := agent.BuildAgentEnv(cfg, d, cwd, agent.WithFallbackPlanBackend(myFallback))
 ```
 
 The fallback is only used when no `task_create` MCP tool is found. If a task

prompts/SYSTEM_PROMPT.md

@@ -58,7 +58,7 @@ cat ${OLLIE_9MOUNT:-$HOME/mnt/ollie}/sk/<name>.md                # load a skill
 
 # Environment
 
-Working directory: {{.WorkDir}}
+Working directory: {{.CWD}}
 Platform: {{.Platform}}
 Current date: {{.Date}}
 Is git repo: {{.IsGitRepo}}